1. Field of the Invention
The present invention relates to apparatus for compacting powder into a generally spherical form. More particularly, it relates to an improved punch and die arrangement for such apparatus in which the counterpunch does not penetrate the die bore during the compaction step.
2. Description of the Prior Art
The present invention is concerned with improved tooling for use in powder-compacting presses such as are disclosed in U.S. Pat. Nos. 3,826,599; 3,775,032; 3,730,659; 3,726,622; 3,645,658; 3,574,892; 3,561,056; 3,415,142; 3,344,213 and 3,328,840, all of which are assigned to the same assignee as the present invention.
In the powder-compacting presses disclosed in the aforementioned U.S. patents, the articles are compacted and formed in a multi-cavity die forming part of a punch and die set, with the finished articles being automatically ejected from the die cavities, picked up by a vacuum pick-up head, and conveyed into suitable receptacles. A work station positioner assembly, which is part of the press, is mounted angularly movable transversely over the die plate and carries a powder dispenser, an anvil and the pick-up head. The powder dispenser, which is supplied with powder from a primary powder supply means connected thereto by means of a flexible tubing or the like, is first positioned over the die cavity or cavities which are thus filled with powder as the punches are displaced downwardly so as to draw a predetermined amount of powder into the die cavity or cavities. The dispenser is then removed from above the die cavity or cavities by the subsequent angular motion of the station positioner assembly, and the anvil is, in turn, positioned over the die cavities. The anvil is clamped over the die cavity by means of a pivotable clamp supported about the anvil and actuated in timed relation with the movement of the punches. The anvil is held down with sufficient pressure to permit the compaction of the powder against the anvil as a result of an upward motion of the punches into the die cavity or cavities. The anvil is then removed from its position over the die cavity or cavities and is replaced by the pick-up head by a further angular motion of the work station positioner transversely across the face of the die plate. The punches are disposed upwardly so as to bring their upper ends in substantial flush alignment with the upper surface of the die plate, such that the finished compacted articles are ejected from the die cavities and picked up by the pick-up head. As the result of a return angular motion of the work station positioner to the initial fill position, the pickup head is removed from over the die cavity and is disposed over one or, if a plurality of die cavities are employed, a series of discharge apertures arranged in a disposition similar to the arrangement of the die cavities in the die plate, and the finished compacted article or articles are drawn, as by vacuum, through the discharge aperture or apertures into a container or separate containers.
The tooling used in the prior art for compacting powder materials into spherical articles consists of a die having a center bore and upper and lower punches, the faces of which define hemispherical cavities. Powder material is charged in a measured quantity into die bore and hemispherical cavity of the lower punch. The upper punch is then moved through the bore and compacts the powder in the spherical cavity defined by the upper and lower punches. Thus, compaction of the powder material is effectuated by movement of the upper punch and the compacted article is positioned entirely within the confines of the die bore prior to ejection.
The present invention provides an apparatus for producing a compacted spherical article partly in a die bore rather than entirely within the bore.